I have a theory....
It would appear by all intensive purposes that yes infact sarada is karin + sasukes daughter but I have another theory.
Sasuke has already seen sarada's basic sharingan. This is all a game sasuke is playing to further advance his child. He knows by going through this fake ordeal he has implanted in her(kind of like itachi did) she will awaken her eye powers so that they may be on the level with the best of them...
tl;dr karin mother is all a lie, its sasukes way of awakening her eyes like itachi did to him.
It would appear by all intensive purposes that yes infact sarada is karin + sasukes daughter but I have another theory.
Sasuke has already seen sarada's basic sharingan. This is all a game sasuke is playing to further advance his child. He knows by going through this fake ordeal he has implanted in her(kind of like itachi did) she will awaken her eye powers so that they may be on the level with the best of them...
tl;dr karin mother is all a lie, its sasukes way of awakening her eyes like itachi did to him.